Regualtion of visceral smooth muscle-specific gene expression during development.

描述（由申请人提供）：不同组织中的平滑肌细胞（SMCs）表达不同的蛋白质群，赋予每个组织独特的生理特性。然而，很少有研究全面定义了负责SMCs这些组织特异性特性的转录调控网络。本提案中描述的实验将通过定义在胃肠道不同组织中指导SMCs基因表达的转录调控网络，开始填补我们知识中的这一空白。解开这些机制对于理解许多肠道疾病的病理至关重要，这些疾病与平滑肌特异性蛋白表达变化导致的收缩性改变有关。我们的初步研究表明，终端蛋白启动子为分析调节基因表达的转录因子提供了一个独特的模型系统，特别是在GI SMCs中。我们认为，Sox和SMAD蛋白与SRF和其他与AT/CArG（-90至-56）区域结合的因子共同作用，在胃肠道SMCs中特异地驱动了端粒蛋白的表达。为了验证这一假设，提出了三个具体目标。对于Aim 1，将确定Sox和SMAD蛋白在调节端粒蛋白表达中的生理作用。此外，还将证实端粒蛋白启动子中Sox和SMAD结合位点对体内GI SMC表达的重要性。我们之前的研究已经确定了几个与末端蛋白启动子中的AT/CArG元件结合的反式作用因子。Aim 2中描述的实验将确定这些因子中哪些与Sox和SMAD蛋白合作，指导GI SMC中的端粒蛋白基因表达。与AT/CArG区域结合的蛋白之一是Foxf1，已发表和初步数据表明Foxf1在胃肠道发育中起重要作用，该蛋白的功能将在平滑肌特异性敲除该基因的小鼠中进一步研究（Aim 3）。总之，这些研究将使我们能够确定控制胃肠道平滑肌组织中收缩蛋白表达的转录调控网络。未来的研究将研究这些转录因子的表达如何在影响胃肠道运动的疾病中改变。这将使我们能够将特定转录因子的变化与收缩蛋白表达的改变以及随后病变组织收缩性的改变联系起来。

DESCRIPTION (provided by applicant): Smooth muscle cells (SMCs) in different tissues express distinct groups of proteins that give each tissue unique physiological properties. However, few studies have comprehensively defined the transcription regulatory networks that are responsible for these tissue-specific properties of SMCs. Experiments described in this proposal will begin to fill this gap in our knowledge by defining the transcription regulatory networks that direct gene expression in SMCs in different tissues of the GI tract. Unraveling these mechanisms is crucial for understanding the pathology of many intestinal diseases that are associated with altered contractility resulting from changes in expression of smooth muscle-specific proteins. Our preliminary studies have demonstrated that the telokin promoter provides a unique model system for the analysis of transcription factors that regulate gene expression, specifically in GI SMCs. We propose that Sox and SMAD proteins, which bind to the -190 to -90 region of the telokin promoter, collaborate with SRF and other factors that bind to the AT/CArG (-90 to -56) region, to drive telokin expression specifically in SMCs of the GI tract. Three specific aims are proposed to test this hypothesis. For Aim 1, the physiological roles of Sox and SMAD proteins in regulating telokin expression will be determined. In addition, the importance of the Sox and SMAD binding sites in the telokin promoter for expression in GI SMC in vivo will be confirmed. Our previous studies have identified several trans-acting factors that bind to the AT/CArG elements in the telokin promoter. Experiments described in Aim 2 will determine which of these factors cooperate with Sox and SMAD proteins to direct telokin gene expression in GI SMC. One of the proteins that binds to the AT/CArG region is Foxf1 and as published and preliminary data suggest that Foxf1 plays an important role in GI tract development, the function of this protein will be further investigated in mice harboring a smooth muscle-specific knockout of the gene (Aim 3). Together these studies will allow us to identify the transcription regulatory network that controls expression of contractile proteins in GI smooth muscle tissues. Future studies, will examine how expression of these transcription factors is altered in diseases that affect GI motility. This will allow us to link changes in specific transcription factors to altered expression of contractile proteins and subsequent altered contractility of diseased tissue. Project Narrative: The goal of our studies is to identify the transcription factors that control the differentiation state of gastrointestinal smooth muscle cells. The differentiation state of smooth muscle is altered, resulting in impaired contractility, in numerous pathological conditions such as Crohns disease, inflammatory bowel disease, idiopathic megacolon and Hirschsprungs disease. Identifying the transcription factors that are dysregulated is an essential step towards designing appropriate therapeutic agents to treat the motility defects that occur in these diseases.